[libertyac]

Perhaps there is, but then , that is the object of this exercise-to explore ALL the possibilities.
Once I have all the information I need, who knows, remedial action may take the form of replacing the helmsman, or indeed, the engineer,with say, an experienced tugboat or yacht person.
As for this post, I am considering it closed to General Discussion but please feel free to contact me via Private Message, should you want to know or contribute more. The History of this boat is far from conventional and many were surprised and some even impressed that the boat completed the 4000-odd miles without major problems-a tribute both to the builders and the crew who prepared her.
Thanks

[Marmot]

Originally Posted by libertyac

"... should you want to know or contribute more. The History of this boat is far from conventional and many were surprised and some even impressed that the boat completed the 4000-odd miles without major problems ..."

So if there is more why are you so defensive about sharing the information? You might have had some good leads already if you had provided all the information upfront. Not to mention that your experience might save some other operator a lot of problems in the future.

[Capt J]

I have seen on some yachts that I've run with extensions on them, where the builder of the extension put a small keel on the extension part that stuck down about a foot for the length of the extension. This may or may not help and you would need to talk to a naval architect about that. I have also seen where the main keel was lengthened. But keeping the most amount of weight in the stern (ie. fuel and/or water) helps greatly in a following sea or current. I've seen on boat with extensions that a following current exudes a lot more side to side swinging of the stern of the vessel over a following sea. (within reason.)

One also has to know be very familiar of the proper running angle of the vessel they're running with an extension. If you drain too much fuel off the bow, and the fuel in the stern is too heavy it will start slowing you down too. It doesn't take much of an off balance. On that 75' Hatteras 50 gallons too much fuel off the bow once you pass the sweet spot and she really starts slowing down.

[NYCAP123]

In the original post libertyac mentioned "entering Ixtapa inlet". As we all know inlets tend to build swells and generate strong currents except at slack tide even "in dead-calm weather", and even a slight opposing breeze can exacerbate the situation. Not being on the helm he would only see the result and possibly hear the skipper cursing as he fought for control. So from what he said of the handling it was a pretty safe bet they were coming through on the inbound tide with a following current.
BTW libertyac, do NOT mention the name of that boat. It could be a bad career move.

[Loren Schweizer]

There were quite a few 58 Bertram Motoryachts extended to 68 feet with unchanged running gear. For the few that actually got into conditions (big quartering aft seas, for example) that warranted some extra helsmanship, the recommendation from the NA was to extend the chord of the rudders 6"+ for more lift, i.e., bite during slow speed ops.

[Adventure]

For years I was the captain of the MOJO (it was famous for that picture of it leaving Morro Bay in the 1978 with George C. Scott aboard) I drove it after it had been extended from 83' to 100' without moving the running gear. She is a wanderer. I would let some other captain drive and they would start getting "out of control". After years of watching people struggle with driving MOJO I figured the problem to be from over steering. They keep correcting from one problem to the next, until they are all over the place. I found the MOJO to be easy to drive and even dock after years of driving it. Not to make judgement on the person at the helm at the time, maybe they just weren't use to the handling and the wheel corrections they were making just snowballed out of control. I find the forward running gear takes longer to respond and you have to be back on center rudder before the vessel has even finished your previous rudder command. We also did leave the aft fuel tanks full to help it's handling. For years I was concerned with MOJO in following seas because of her extension and she was built of wood, but never had a problem. I always thought the worse thing is I leave the harbor a 100' long and return 83' long.

[NYCAP123]

I always thought the worse thing is I leave the harbor a 100' long and return 83' long.

That's a dream/nightmare several had although I can't say I ever heard of it happening. Some bad welds and other things yes.

I found the MOJO to be easy to drive and even dock after years of driving it.

If several had problems oversteering it's a safe bet it's the boat. Doesn't mean its undrivable. All boats have their querks and we learn to deal with them.